Rheological Properties of PC/EVA Blend Compatibilized with the Transesterification

The rheological properties of PC/EVA blends had been investigated by a Haake torque rheometer. The effects of blending temperature, a polycarbonate and a catalyst on the rheological properties of PC/EVA blends were discussed. The transesterification between PC and EVA, catalyzed by dibutyl tin oxide (DBTO), were investigated by differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results indicate that the chain break of PC or EVA can be accelerated by DBTO, which induces the equilibrium torque of PC or EVA to decrease as the DBTO content increases. But for the PC/EVA blend, as the blending temperature of increases, the increase of viscosity induced by the generation of the PC-EVA copolymer exceeds the decrease of viscosity induced by the chain break of PC and EVA. Therefore, the equilibrium torque of the PC/EVA blend with varying DBTO content is higher than that of uncatalyzed PC/EVA blend at the higher temperature, 250°C, compared with the lower temperature, 210°C. The content of PC in the blend influences the probability of transesterification and the generation of PC-EVA copolymer. The PC/EVA blend with 50 wt. %PC has the highest torque compared with the other blends.     

High-Area Ti/Pt Electrodes for the Electrochemically Catalyzed Transesterification of Soybean Oil with Methanol

Biodiesel fuel is a renewable energy source normally produced in industry by using an alkaline homogeneous catalyst to promote the transesterification of oil and methanol to fatty acid methyl ester (FAME). Undesirable side reactions occur when poorly refined oils are used, leading to serious problems of product separation and low FAME yield. Therefore, about 85% of the cost of biodiesel is determined by the cost of the feedstock. Here, we describe the development of high-area Pt films deposited on Ti substrates for the electrolytic synthesis of biodiesel from soybean oil containing water, without the addition of catalyst. The higher both the calcination temperature and the number of layers deposited on the Ti surface, the higher the electrochemically active area of Pt exposed to surface. Conversion into esters in electrolysis is proportional to the increase in the superficial area of the Ti/Pt electrodes. Thus, it is possible to synthesize biodiesel using electrodes containing very low amounts of Pt (<0.441 mg cm^?2), an important parameter in the industrial production of biodiesel.     

Polyol-Derived Alkoxide/Hydroxide Base Catalysts II: Transesterification Reactions

Biodiesel, fatty acid methyl ester (FAME), was produced by transesterification of canola oil with methanol in the presence of a series of alkoxide/hydroxide base catalysts produced from glycerol, 1,2-propanediol, 1,3-propanediol, xylitol, or sorbitol produced by dehydration reaction of sodium hydroxide in the presence of polyols. Transesterification reactions proceeded efficiently in the presence of sodium alkoxide catalysts prepared at three different mole ratios of sodium hydroxide to glycerol (1:1, 2:1, and 3:1). The production of methyl ester during the course of the reaction was determined repeatedly and the reaction progress was compared with that achieved in a reaction catalyzed by freshly prepared anhydrous sodium methoxide as a standard catalyst. Sodium alkoxide/hydroxide catalysts activity during the first 2 min of the reaction was in the order of: sorbitol < xylitol < sodium methoxide < 1,2-propanediol < 1,3-propanediol < glycerol regardless of the mole ratio of sodium hydroxide to glycerol. All catalysts showed a higher methyl ester accumulation at higher ratios of sodium hydroxide to polyol and had the following order 1:1 < 2:1 < 3:1 (sodium hydroxide:glycerol). Several of these catalysts were as powerful as sodium methoxide in catalyzing the transesterification reaction at the same mole concentration. All alkoxide/hydroxide catalysts resulted in a high FAME accumulation (>95 wt%) in a single transesterification batch reaction.     

Performance evaluation of a vegetable oil fuelled compression ignition engine

Fuel crisis because of dramatic increase in vehicular population and environmental concerns have renewed interest of scientific community to look for alternative fuels of bio-origin such as vegetable oils. Vegetable oils can be produced from forests, vegetable oil crops, and oil bearing biomass materials. Non-edible vegetable oils such as linseed oil, mahua oil, rice bran oil, etc. are potentially effective diesel substitute. Vegetable oils have high-energy content. This study was carried out to investigate the performance and emission characteristics of linseed oil, mahua oil, rice bran oil and linseed oil methyl ester (LOME), in a stationary single cylinder, four-stroke diesel engine and compare it with mineral diesel. The linseed oil, mahua oil, rice bran oil and LOME were blended with diesel in different proportions. Baseline data for diesel fuel was collected. Engine tests were performed using all these blends of linseed, mahua, rice bran, and LOME. Straight vegetable oils posed operational and durability problems when subjected to long-term usage in CI engine. These problems are attributed to high viscosity, low volatility and polyunsaturated character of vegetable oils. However, these problems were not observed for LOME blends. Hence, process of transesterification is found to be an effective method of reducing vegetable oil viscosity and eliminating operational and durability problems. Economic analysis was also done in this study and it is found that use of vegetable oil and its derivative as diesel fuel substitutes has almost similar cost as that of mineral diesel.     

固体超强碱催化合成生物柴油

以猪油和甲醇为原料,在固体超强碱催化作用下,发生酯交换反应合成生物柴油;考察了醇油摩尔 比,催化剂质量分数,反应时间,反应温度对生物柴油回收率的影响。结果表明,醇油摩尔比为9∶1,催化剂质量为 动物油质量的2%,70℃反应3h为较理想的反应条件。     

PET／PEN共混物结构和性能的研究

在控制熔融共混温度和时间的前提下制备了一系列配比不同的PET／PEN共混物,通过NMP、WAXS、DSC和DMA等手段对共混物的结构特别是酯交换反应的情况进行了研究。发现在所选定的低熔融温度、较短熔融共混时间等条件下,PET与PEN之间基本未发生酯交换反应,熔融挤出产物中PET和PEN两组分仍然保持着各自分子链的规整性,在加热时仍然可以独自结晶。     

Biodiesel production from inedible animal tallow and an experimental investigation of its use as alternative fuel in a direct injection diesel engine

In this study, a substitute fuel for diesel engines was produced from inedible animal tallow and its usability was investigated as pure biodiesel and its blends with petroleum diesel fuel in a diesel engine. Tallow methyl ester as biodiesel fuel was prepared by base-catalyzed transesterification of the fat with methanol in the presence of NaOH as catalyst. Fuel properties of methyl ester, diesel fuel and blends of them (5%, 20% and 50% by volume) were determined. Viscosity and density of fatty acid methyl ester have been found to meet ASTM D6751 and EN 14214 specifications. Viscosity and density of tallow methyl esters are found to be very close to that of diesel. The calorific value of biodiesel is found to be slightly lower than that of diesel. An experimental study was carried out in order to investigate of its usability as alternative fuel of tallow methyl ester in a direct injection diesel engine. It was observed that the addition of biodiesel to the diesel fuel decreases the effective efficiency of engine and increases the specific fuel consumption. This is due to the lower heating value of biodiesel compared to diesel fuel. However, the effective engine power was comparable by biodiesel compared with diesel fuel. Emissions of carbon monoxide (CO), oxides of nitrogen (NO_x), sulphur dioxide (SO₂) and smoke opacity were reduced around 15%, 38.5%, 72.7% and 56.8%, respectively, in case of tallow methyl esters (B100) compared to diesel fuel. Besides, the lowest CO, NO_x emissions and the highest exhaust temperature were obtained for B20 among all other fuels. The reductions in exhaust emissions made tallow methyl esters and its blends, especially B20 a suitable alternative fuel for diesel and thus could help in controlling air pollution. Based on this study, animal tallow methyl esters and its blends with petroleum diesel fuel can be used a substitute for diesel in direct injection diesel engines without any engine modification.     

酯交换法合成碳酸二苯酯催化剂的研究

碳酸二苯酯是重要的有机中间体,应用于塑料工业。酯交换法合成碳酸二苯酯是替代光气法的新型绿色合成工艺。笔者概述了碳酸二苯酯酯交换法的合成工艺,并对催化剂研究作了介绍。     

聚碳酸酯非光气法合成工艺研究进展

综述了近年来聚碳酸酯的酯交换法合成工艺的研究进展,着重阐述了其预聚反应动力学,介绍了该工艺中传热传质等因素对聚合过程的影响以及国内外相关研究现状和研究前景。     

Homogene oder heterogene Katalyse? Simultane Verwendung von basischen und sauren Zeolithen in der flüssigen Phase bei der Umesterung und Veresterung

Base catalyzed transesterification of triglycerides with methanol was studied in liquid phase on a K-LSX zeolite. The presence of free fatty acid results in its deactivation. Their esterification was catalyzed by an acidic H-Y zeolite. Surprisingly, in case of mixing of both catalysts, no catalytic activity was observed. Consequently, both reactions should proceed homogeneously because the formation of the intermediate methylat ion is suppressed. This could be explained in term of a fast ion exchange between the K⁺ ions of K-LSX and the H⁺ ions of Y-zeolite. On the other hand, the observed transport limitation indicates on a heterogeneously catalyzed reaction. Therefore, in case of even non-aqueous liquid phase reactions, a contribution of a homogeneous reaction path must be considered.